Panthethine or pantetheine is a useful compound as a precursor of co-enzyme A which plays an important part in energy metabolism, lipid metabolism and acetylation reaction in vivo.
Heretofore, the following methods of synthesizing pantethine or pantetheine have been known:
A. Method in which pantothenic acid is once activated into the form of ester, azide and mixed anhydride etc., and thereafter condensed with cystamine or cysteamine (Japanese Patent Application Publications Nos. 77/55 and 467/58, U.S. Pat. No. 2,625,565).
B. Method in which ethyleneimide derivative of pantothenic acid is caused to open its ring by means of hydrogen sulfide etc. and is thereafter oxidized (Japanese Patent Application Publications Nos. 23934/68 and 24649/68).
C. Method of condensing alethine derivative and pantolactone (Japanese Patent Application Publication No. 4672/56).
D. Method in which pantothenonitrile and cystamine are caused to react resulting in the formation of thiazoline ring, and this is caused to open the ring, and oxidized (Japanese Patent Application Publications Nos. 10149/65, 13848/65 and 28929/65).
E. Method in which both or one of salts of pantothenic acid and cystamine are subjected to a pretreatment and thereafter condensed (Japanese Patent Application Publications Nos. 2896/66, 26490/72 and 3324/69, Japanese Patent Application Laying-Open Publication No. 76816/73).
These methods (A)-(D) require reactions of several stages from the starting materials to the products, and the refining in each stage and the product is very difficult and as a result it is inevitable that by-product in each reaction is mixed into the product resulting in making it difficult to obtain pantethine of high purity. In the method (E), it is necessary that both or one of the starting raw materials is in the form of liberation, and since the by-products which are difficult to be refined off are produced, satisfactory products in purity can not be obtained.
The above described prior art methods are not sufficiently satisfactory as industrial methods because of multi reaction stages, production of by-products in such a reaction, complication of production steps, use of special raw materials and secondary raw materials which can not be easily obtained, and difficulties such as lowering of product purity, etc.